It is well known that the transmission of high speed data signals, such as video signals, over a data link can give rise to both electromagnetic and electric field emissions around the data communication link. Where such high speed data communication links are used in proximity to field sensitive devices such as microprocessors and microcontrollers, significant operating interference issues can arise.
The greatest electromagnetic interference (EMI) and electric field interference (EFI) occurs from the use of unshielded parallel wire communication links or lines. A substantial reduction in EMI can be achieved through the use of twisted-pair wires because of the electromagnetic field canceling effect of the twisting characteristic. Even where the twisting is very tight, however, the solution for the reduction of EMI is only partial.
Of course both EMI and EFI can be totally eliminated through the use of optical fiber data communication links, but it is not always convenient or economically feasible to provide electro-optical conversion components in, for example, an automotive application where all other high speed and low speed data links are of the electrical type.